Thursday, January 11, 2018

What does antiseptic preparation do to skin bacteria?

It is recognized that the complex and diverse skin micro biome provides protection agains pathogenic skin microorganisms. While antimicrobial agents are largely employed to reduce infection by pathogenic microorganisms these treatments can also act on resident cutaneous species. This is especially true for antiseptics, a group of antimicrobial agents used specifically for their indiscriminate mechanisms of action. Antiseptics are a mainstay of modern medicine, but have also infiltrated daily routines in the form of gels, wipes, and sprays designed to sterilize the skin.

These authors point out that it is unclear how resident skin microbial communities are altered by topical antimicrobial interventions commonly used in personal and clinical settings.

In this investigation they show that acute exposure to antiseptic treatments elicits rapid but short-term depletion of microbial community diversity and membership.

Thirteen subjects were enrolled in a longitudinal treatment study to analyze the effects of topical treatments on the skin microbiome at two skin sites of disparate microenvironment: forearm and back.

They found that changes to community membership were largely driven by a decrease in bacterial diversity, with water, alcohol, and povidone-iodine all significantly reducing the number of observed species compared to adjacent controls. Lowly abundant members of the skin microbiota were more likely to be displaced, and subsequently replaced by the most abundant taxa prior to treatment. Of particular interest to shoulder surgeons is the finding that members of the skin commensal family Propionibactericeae were particularly resilient to treatment, suggesting a distinct competitive advantage after antiseptic use: decreases in the relative proportions of most taxa were offset by increases in Propionibacteriaceae. They suggest that the persistence of Propionibacteriaceae could be due to their inherent resilience or to their increased abundance at deeper layers of the skin. Regardless, the persistence of this organism likely represents a unique opportunity for it to thrive in the post-treatment setting.

Comment: This study shows what may be an unintended consequence of the use of antiseptics: selection for Priopionibacterium at the expense of healthy microbial diversity.